Propellers for model aircraft are usually difficult to maintain and to prevent their being broken. Such aircraft, because it is invariably radio controlled, frequently have minor landing accidents and unfortunately, it is generally the propreller that is damaged. Thus two-bladed wood propellers are normally used, since they are relatively inexpensive, of light weight, strong, and have good shock absorbing characteristics upon impact. Two-bladed propellers, however, are very noisy and not as efficients as the three-bladed kind, which are much more expensive and are more quiet.